Answer:
The cohort effect is a big problem for research in sociology and epidemiology, as well as in psychology because it´s a research outcome that has been influenced by the features of the cohort under study, given that they all share common historical and social experiences. The cohort effects are particularly problematic in cross-sectional methods.
Explanation:
For example, the research could conclude that older people find it easier to put together a puzzle. However, the results could be tainted by the cohort effect in that putting together a puzzle is an activity that older participants are more likely to have done in the past, opposite to younger participants raised in a more technological time.